Phosphor substrate, light emitting substrate, and lighting device

ABSTRACT

A phosphor substrate having at least one light emitting element mounted on one surface, includes an insulating substrate, at least one electrode pair disposed on one surface of the insulating substrate and bonded to the light emitting element, and a phosphor layer disposed on one surface of the insulating substrate, including a phosphor in which a light emission peak wavelength, in a case where light emitted by the element is used as excitation light, is in a visible light region, in which a bonded surface of the electrode pair facing an outer side in a thickness direction of the insulating substrate, the bonded surface being bonded to the light emitting element, is positioned further on the outer side in the thickness direction than a non-bonded surface other than the bonded surface, and at least a part of the phosphor layer is disposed around the bonded surface of the one surface.

TECHNICAL FIELD

The present invention relates to a phosphor substrate, a light emittingsubstrate, and a lighting device.

BACKGROUND ART

Patent Document 1 discloses an LED lighting equipment including asubstrate on which a light emitting element (LED element) is mounted. Inthis LED lighting equipment, a reflective material is provided on asurface of the substrate to improve light emitting efficiency.

RELATED DOCUMENT Patent Document

[Patent Document 1] Chinese Patent Publication No. 106163113

SUMMARY OF THE INVENTION Technical Problem

However, in a case of a configuration disclosed in Patent Document 1, itis not possible to adjust light emitted by the LED lighting equipment bythe reflective material to light having a light emission color differentfrom the light emitted by the light emitting element.

An object of the present invention is to provide a phosphor substratecapable of adjusting light emitted from the phosphor substrate, in acase where a light emitting element is mounted, to light having anemission color different from light emitted by the light emittingelement.

Solution to Problem

A phosphor substrate according to a first aspect of the presentinvention is a phosphor substrate having at least one light emittingelement mounted on one surface, and includes an insulating substrate, anelectrode layer disposed on one surface of the insulating substrate andbonded to the light emitting element, and a phosphor layer which isdisposed on one surface of the insulating substrate and includes aphosphor in which a light emission peak wavelength, in a case wherelight emitted by the light emitting element is used as excitation light,is in a visible light region, in which a bonded surface of a surface ofthe electrode layer facing an outer side in a thickness direction of theinsulating substrate, the bonded surface being bonded to the lightemitting element, is positioned further on the outer side in thethickness direction than a non-bonded surface which is a surface otherthan the bonded surface, and at least a part of the phosphor layer isdisposed around the bonded surface.

A phosphor substrate according to a second aspect of the presentinvention is a phosphor substrate having a plurality of light emittingelements mounted on one surface, and includes an insulating substrate,an electrode layer disposed on one surface of the insulating substrateand bonded to the plurality of light emitting elements, respectively,and a phosphor layer which is disposed on one surface of the insulatingsubstrate and includes a phosphor in which a light emission peakwavelength, in a case where light emitted by the plurality of lightemitting elements is used as excitation light, is in a visible lightregion, in which a bonded surface of a surface of the electrode layerfacing an outer side in a thickness direction of the insulatingsubstrate, the bonded surface being bonded to the light emittingelement, is positioned further on the outer side in the thicknessdirection than a non-bonded surface which is a surface other than thebonded surface, and at least a part of the phosphor layer is disposedaround the bonded surface.

In the phosphor substrate according to a third aspect of the presentinvention according to the phosphor substrate according to the secondaspect, at least a part of the phosphor layer is disposed in a regionother than a region of the one surface of the insulating substrate wherethe electrode layer is disposed.

In the phosphor substrate according to a fourth aspect of the presentinvention according to the phosphor substrate according to the second orthird aspect, at least a part of the phosphor layer is disposed on thenon-bonded surface.

In the phosphor substrate according to a fifth aspect of the presentinvention according to the phosphor substrate according to any one ofthe first to fourth aspects, a surface of the phosphor layer on theouter side in the thickness direction is positioned further on the outerside in the thickness direction than the bonded surface.

In the phosphor substrate according to a sixth aspect of the presentinvention according to the phosphor substrate according to any one ofthe first to fifth aspects, the light emitting element is formed as achip sized package (CSP) in which an LED is incorporated.

In the phosphor substrate according to a seventh aspect of the presentinvention according to the phosphor substrate according to the sixthaspect, a correlated color temperature of the phosphor is set to acorrelated color temperature which is different from a correlated colortemperature of a phosphor contained in the CSP.

Here, the “correlated color temperature of the phosphor” means acorrelated color temperature of the light emission color of the phosphor(hereinafter, the same applies).

In the phosphor substrate according to an eighth aspect of the presentinvention according to the phosphor substrate according to the sixthaspect, a correlated color temperature of the phosphor is set to acorrelated color temperature which is the same as a correlated colortemperature of a phosphor contained in the CSP.

A light emitting substrate according to the first aspect of the presentinvention includes the phosphor substrate according to any one of thefirst to eighth aspects, and at least one light emitting element bondedto the bonded surface.

In the light emitting substrate according to the second aspect of thepresent invention according to the light emitting substrates accordingto the first aspect, the light emitting element is formed as a chipsized package (CSP) in which an LED is incorporated.

In the light emitting substrate according to a third aspect of thepresent invention according to the light emitting substrate according tothe second aspect, a correlated color temperature of the phosphor is setto a correlated color temperature which is different from a correlatedcolor temperature of a phosphor contained in the CSP.

In the light emitting substrate of a fourth aspect of the presentinvention according to the light emitting substrate of the secondaspect, a correlated color temperature of the phosphor is set to acorrelated color temperature which is the same as a correlated colortemperature of a phosphor contained in the CSP.

A lighting device of the present invention includes the light emittingsubstrate according to any one of the first to fourth aspects, and apower source which supplies electric power for causing the lightemitting element to emit light.

Advantageous Effects of Invention

According to the phosphor substrate according to the first to eighthaspects of the present invention, it is possible to adjust light emittedfrom the phosphor substrate, in a case where a light emitting element ismounted, to light having an emission color different from light emittedby the light emitting element.

In addition, in the phosphor substrate according to the second to eighthaspects of the present invention, it is possible to reduce glare whileadjusting light emitted from the phosphor substrate, in a case where alight emitting element is mounted, to light having an emission colordifferent from light emitted by the light emitting element. Further, thephosphor substrate according to the eighth aspect of the presentinvention can also exhibit an effect of alleviating a chromaticityvariation of the mounted light emitting element by the phosphor layer.

In addition, in the light emitting substrate of the present invention,it is possible to adjust light emitted from the phosphor substrate tolight having an emission color different from light emitted by the lightemitting element.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects described above, other objects, features and advantages willbe further clarified by the preferred embodiments which will bedescribed later and the accompanying drawings below.

FIG. 1A is a plan view of a light emitting substrate of the presentembodiment.

FIG. 1B is a bottom view of the light emitting substrate of the presentembodiment.

FIG. 1C is a partial cross-sectional view of the light emittingsubstrate taken along a cutting line 1C-1C of FIG. 1A.

FIG. 2A is a plan view of a phosphor substrate of the present embodiment(the phosphor layer is not shown).

FIG. 2B is a plan view of the phosphor substrate of the presentembodiment.

FIG. 3A is an explanatory diagram of a first step in a method formanufacturing the light emitting substrate of the present embodiment.

FIG. 3B is an explanatory diagram of a second step in the method formanufacturing the light emitting substrate of the present embodiment.

FIG. 3C is an explanatory diagram of a third step in the method formanufacturing the light emitting substrate of the present embodiment.

FIG. 3D is an explanatory diagram of a fourth step in the method formanufacturing the light emitting substrate according to the presentembodiment.

FIG. 3E is an explanatory diagram of a fifth step in the method formanufacturing the light emitting substrate according to the presentembodiment.

FIG. 4 is a diagram for explaining a light emitting operation of thelight emitting substrate of the present embodiment.

FIG. 5 is a diagram for explaining a light emitting operation of a lightemitting substrate of a comparative embodiment.

FIG. 6 is a graph showing a result of a first test of a correlated colortemperature of the light emitting substrate of the present embodiment.

FIG. 7 is a graph showing a result of a second test of the correlatedcolor temperature of the light emitting substrate of the presentembodiment.

DESCRIPTION OF EMBODIMENTS

<<Overview>>

Hereinafter, a configuration and function of a light emitting substrate10 of the present embodiment will be described with reference to FIGS.1A to 1C, 2A, and 2B. Then, a method for manufacturing the lightemitting substrate 10 of the present embodiment will be described withreference to FIGS. 3A to 3E. Next, a light emitting operation of thelight emitting substrate 10 of the present embodiment will be describedwith reference to FIG. 4. After that, effects of the present embodimentwill be described with reference to FIGS. 4 to 7 and the like. In allthe drawings referred to in the following description, the samereference numerals are used for the same constituent elements and thedescription thereof will not be repeated.

<<Configuration and Function of Light Emitting Substrate of PresentEmbodiment>>

FIG. 1A is a plan view of the light emitting substrate 10 of the presentembodiment (view seen from a front surface 31), and FIG. 1B is a bottomview of the light emitting substrate 10 of the present embodiment (viewseen from a rear surface 33). FIG. 1C is a partial cross-sectional viewof the light emitting substrate 10 taken along a cutting line 1C-1C ofFIG. 1A.

The light emitting substrate 10 of the present embodiment is rectangularas an example, when seen from the front surface 31 and the rear surface33. In addition, the light emitting substrate 10 of the presentembodiment includes a plurality of light emitting elements 20, aphosphor substrate 30, and electronic components (not shown) such as aconnector, a driver IC, and the like. That is, in the light emittingsubstrate 10 of the present embodiment, the plurality of light emittingelements 20 and the electronic components are mounted on the phosphorsubstrate 30.

The light emitting substrate 10 of the present embodiment has a functionof emitting light, in a case where power is supplied from an externalpower source (not shown) by directly attaching a lead wire or through aconnector. Accordingly, the light emitting substrate 10 of the presentembodiment is used as a main optical component in, for example, alighting device (not shown).

<Plurality of Light Emitting Elements>

As an example, each of the plurality of light emitting elements 20 isformed as a Chip Scale Package (CSP) in which a flip chip LED 22(hereinafter, referred to as an LED 22) is incorporated (see FIG. 1C).As the CSP, as shown in FIG. 1C, it is preferable that the entirecircumference (five surfaces) except a bottom surface of the LED 22 iscovered with a phosphor sealing layer 24. The phosphor sealing layer 24contains a phosphor, and light of the LED 22 is color-converted by thephosphor of the phosphor sealing layer 24 and emitted to the outside. Asshown in FIG. 1A, the plurality of light emitting elements 20 aremounted on the phosphor substrate 30 in a state of being regularlyarranged on the front surface 31 (an example of one surface) of thephosphor substrate 30 over the entire front surface 31. A correlatedcolor temperature of the light emitted by each light emitting element 20of the present embodiment is set to 3,018K as an example. In addition,the plurality of light emitting elements 20 use a heat sink (not shown)and a cooling fan (not shown) during the light emitting operation todissipate heat (cool) the phosphor substrate 30 to be, for example, roomtemperature to 50° C. to 100° C. Here, to supplement the meaning of “to”used in the numerical range in the present specification, for example,“50° C. to 100° C.” means “equal to or higher than 50° C. and equal toor lower than 100° C.”. In addition, “to” used in the numerical range inthis specification means “equal to or more than the description partbefore “to” and equal to or less than the description part after “to”.

<Phosphor Substrate>

FIG. 2A is a view of the phosphor substrate 30 of the present embodimentand is a plan view (seen from the front surface 31) in which thephosphor layer 36 omitted. FIG. 2B is a plan view (seen from the frontsurface 31) of the phosphor substrate 30 of the present embodiment. Thebottom view of the phosphor substrate 30 of the present embodiment isthe same as the view of the light emitting substrate 10 seen from therear surface 33. In addition, the partial cross-sectional view of thephosphor substrate 30 of the present embodiment is the same as the viewwhen the light emitting element 20 is removed from the partialcross-sectional view of FIG. 1C. That is, the phosphor substrate 30 ofthe present embodiment is rectangular as an example, when seen from thefront surface 31 and the rear surface 33.

The phosphor substrate 30 of the present embodiment includes aninsulating layer 32 (an example of an insulating substrate), anelectrode layer 34, a phosphor layer 36, and a rear surface patternlayer 38 (see FIGS. 1B, 1C, and 2A, and 2B). Although the phosphor layer36 is not shown in FIG. 2A, the phosphor layer 36 is, for example,disposed on a portion of the front surface 31 of the insulating layer 32and the electrode layer 34, other than a plurality of electrode pairs34A which will be described later, as shown in FIG. 2B.

In addition, as shown in FIGS. 1B and 2A, the phosphor substrate 30 isformed with six through holes 39 at four portions near the four cornersand two portions near the center. The six through holes 39 are used aspositioning holes during the manufacturing of the phosphor substrate 30and the light emitting substrate 10. In addition, the six through holes39 are used as mounting screw holes for ensuring a heat-drawing effect(preventing warping and floating of the substrate) of a (light emitting)lamp housing. As will be described later, the phosphor substrate 30 ofthe present embodiment is manufactured by processing (etching or thelike) a double-sided plate (hereinafter, referred to as a motherboardMB. see FIG. 3A) in which copper foil layers are provided on both sidesof an insulating plate, and CS-3305A manufactured by Risho Kogyo Co.,Ltd. is used as an example of the motherboard MB.

[Insulating Layer]

Hereinafter, main features of the insulating layer 32 of the presentembodiment will be described.

As described above, a shape thereof is, for example, rectangular whenseen from the front surface 31 and the rear surface 33.

A material thereof is, for example, an insulating material containing abismaleimide resin and a glass cloth.

A thickness thereof is, for example, 100 μm to 200 μm.

Coefficients of thermal expansion (CTE) thereof in a vertical directionand a horizontal direction are, for example, equal to or less than 10ppm/° C. in a range of 50° C. to 100° C., respectively. From anotherpoint of view, each of the coefficients of thermal expansion (CTE) inthe vertical direction and the horizontal direction is, for example, 6ppm/K. This value is substantially the same as that of the lightemitting element 20 of the present embodiment (90% to 110%, that is,within ±10%).

A glass transition temperature thereof is, for example, higher than 300°C.

A storage elastic modulus is, for example, greater than 1.0×10¹⁰ Pa andsmaller than 1.0×10¹¹ Pa in a range of 100° C. to 300° C.

[Electrode Layer]

The electrode layer 34 of the present embodiment is a metal layerprovided on the front surface 31 side of the insulating layer 32. Theelectrode layer 34 of this embodiment is, for example, a copper foillayer (a layer formed of Cu). In other words, the electrode layer 34 ofthe present embodiment is formed so that at least the surface thereofcontains copper.

The electrode layer 34 has a pattern provided on the insulating layer32, and is electrically connected to a terminal (not shown) to which aconnector (not shown) is bonded. The electrode layer 34 supplieselectric power supplied from an external power source (not shown)through the connector to the plurality of light emitting elements 20 atthe time of configuring the light emitting substrate 10. Accordingly, apart of the electrode layer 34 is the plurality of electrode pairs 34Ato which the plurality of light emitting elements 20 are bonded. Thatis, the electrode layer 34 of the light emitting substrate 10 of thepresent embodiment is disposed on the insulating layer 32 and connectedto each light emitting element 20. From another point of view, theelectrode layer 34 of the phosphor substrate 30 of the presentembodiment is disposed on the insulating layer 32 and connected to eachlight emitting element 20. In addition, as described above, since theplurality of light emitting elements 20 of the light emitting substrate10 of the present embodiment are regularly arranged over the entirefront surface 31, the plurality of electrode pairs 34A are also arrangedover the entire front surface 31 (see FIG. 2A). A portion of theelectrode layer 34 other than the plurality of electrode pairs 34A isreferred to as a wiring portion 34B. In the present embodiment, as shownin FIG. 1C, as an example, the plurality of electrode pairs 34A protrudeoutward from the wiring portion 34B in a thickness direction of theinsulating layer 32 (phosphor substrate 30). In other words, on thesurface of the electrode layer 34 facing the outer side in the thicknessdirection of the insulating layer 32, the surface to which each lightemitting element 20 is bonded (bonded surface 34A1) is positioned on theouter side in the thickness direction of the insulating layer 32,compared to the surface other than the bonded surface 34A1 (non-bondedsurface 34B1).

A region of the front surface 31 of the insulating layer 32 where theelectrode layer 34 is disposed (occupied area of the electrode layer 34)is, for example, a region (area) that is equal to or more than 60% ofthe front surface 31 of the insulating layer 32 (see FIG. 2A).

[Phosphor Layer]

As shown in FIG. 2B, regarding the phosphor layer 36 of the presentembodiment is, for example, the phosphor layer 36 is disposed on aportion of the front surface 31 of the insulating layer 32 and theelectrode layer 34, other than the plurality of electrode pairs 34A.That is, the phosphor layer 36 is disposed in a region of the electrodelayer 34 other than the plurality of electrode pairs 34A. In otherwords, at least a part of the phosphor layer 36 is disposed around eachbonded surface 34A1 on the surface 31 (see FIGS. 1C and 2B). Inaddition, from another point of view, at least a part of the phosphorlayer 36 is disposed so as to surround each bonded surface 34A1 over theentire circumference, when seen from the surface 31 side. In the presentembodiment, the region of the front surface 31 of the insulating layer32 where the phosphor layer 36 is disposed is, for example, a regionthat is equal to or more than 80% of the front surface 31 of theinsulating layer 32.

In the present embodiment, the surface of the phosphor layer 36 on theouter side in the thickness direction of the insulating layer 32 is, forexample, positioned further on the outer side in the thickness directionthan the bonded surface 34A1 of the electrode layer 34 (see FIGS. 1C and3E). However, a configuration opposite to that of the presentembodiment, that is, a configuration in which the surface of thephosphor layer 36 on the outer side in the thickness direction of theinsulating layer 32 is positioned further on an inner side in thethickness direction than the bonded surface 34A1 (not shown) may beused. In addition, a configuration in which the surface of the phosphorlayer 36 on the outer side in the thickness direction of the insulatinglayer 32 is positioned at the same position as the bonded surface 34A1in the thickness direction (not shown) may be used.

The phosphor layer 36 of the present embodiment is, for example, aninsulating layer containing a phosphor and a binder, which will bedescribed later. The phosphor contained in the phosphor layer 36 is fineparticles held in a state of being dispersed in a binder, and has aproperty of exciting the light emitted from the LED 22 of each lightemitting element 20 as excitation light. Specifically, the phosphor ofthe present embodiment has a property that the light emission peakwavelength when the light emitted by the light emitting element 20 isused as excitation light is in a visible light region. The binder maybe, for example, an epoxy-based binder, an acrylate-based binder, or asilicone-based binder, and may have an insulating property equivalent tothat of the binder contained in a solder resist.

(Specific Example of Phosphor)

Here, the phosphor contained in the phosphor layer 36 of the presentembodiment is, for example, at least one or more phosphors selected fromthe group consisting of an α-type sialon phosphor containing Eu, aβ-type sialon phosphor containing Eu, a CASN phosphor containing Eu, anda SCASN phosphor containing Eu. The phosphor described above is anexample of the present embodiment, and may be a phosphor other than thephosphor described above, such as YAG, LuAG, BOS, and other visiblelight-excited phosphors.

The α-type sialon phosphor containing Eu is represented by generalformula: M_(x)Eu_(y)Si_(12−(m+n))Al_((m+n))O_(n)N_(16−n). In the abovegeneral formula, M is at least one or more elements containing at leastCa selected from the group consisting of Li, Mg, Ca, Y, and lanthanideelements (here, excluding La and Ce), and in a case where a valence of Mis a, ax+2y=m, x satisfies 0<x≤1.5, 0.3≤m<4.5, and 0<n<2.25.

The β-type sialon phosphor containing Eu is a phosphor in which divalenteuropium (Eu²⁺) is dissolved as a light emitting center in β-type sialonrepresented by general formula: Si_(6−z)Al_(z)O_(z)N_(8−z) (z=0.005 to1).

In addition, examples of a nitride phosphor include a CASN phosphorcontaining Eu, a SCASN phosphor containing Eu, and the like.

The CASN phosphor containing Eu (an example of a nitride phosphor) is,for example, a red phosphor which is represented by the formulaCaAlSiN₃:Eu²⁺ in which Eu²⁺ is used as an activator and a crystal formedof alkaline earth silicate is used as a base. In the definition of theCASN phosphor containing Eu in the present specification, the SCASNphosphor containing Eu is excluded.

The SCASN phosphor containing Eu (an example of a nitride phosphor) is,for example, a red phosphor which is represented by the formula(Sr,Ca)AlSiN₃:Eu²⁺ in which Eu²⁺ is used as an activator and a crystalformed of alkaline earth silicate is used as a base.

[Rear Surface Pattern Layer]

The rear surface pattern layer 38 of the present embodiment is a metallayer provided on the rear surface 33 side of the insulating layer 32.The rear surface pattern layer 38 of this embodiment is, for example, acopper foil layer (a layer formed of Cu).

As shown in FIG. 1B, the rear surface pattern layer 38 is a layer inwhich a plurality of rectangular blocks arranged linearly along alongitudinal direction of the insulating layer 32 are arranged to beadjacent to each other by shifting phase in a short direction.

The rear surface pattern layer 38 is, for example, an independentfloating layer. In addition, the rear surface pattern layer 38 overlapswith the region that is equal to or more than 80% of the electrode layer34 disposed on the front surface 31, for example, in a thicknessdirection of the insulating layer 32 (phosphor substrate 30).

The above is the description of the configuration of the light emittingsubstrate 10 and the phosphor substrate 30 of the present embodiment.

<<Method for Manufacturing Light Emitting Substrate of PresentEmbodiment>>

Next, a method for manufacturing the light emitting substrate 10 of thepresent embodiment will be described with reference to FIGS. 3A to 3E.The method for manufacturing the light emitting substrate 10 of thepresent embodiment includes a first step, a second step, a third step, afourth step, and a fifth step, and each step is performed in this order.

<First Step>

FIG. 3A is a diagram showing a start time and an end time of the firststep. The first step is a step of forming a pattern 34C that is the sameas the electrode layer 34, when seen from the thickness direction, onthe front surface 31 of the motherboard MB, and the rear surface patternlayer 38 on the rear surface 33. This step is performed, for example, byetching using a mask pattern (not shown).

<Second Step>

FIG. 3B is a diagram showing a start time and an end time of the secondstep. The second step is a step of half-etching (etching halfway in thethickness direction) of a part of the pattern 34C. In a case where thisstep ends, as a result, the electrode layer 34 including the pluralityof electrode pairs 34A and the wiring portion 34B is formed. That is, ina case where this step ends, the plurality of bonded surfaces 34A1 andthe plurality of non-bonded surfaces 34B1 are formed on the electrodelayer 34. This step is performed, for example, by etching using a maskpattern (not shown).

<Third Step>

FIG. 3C is a diagram showing a start time and an end time of the thirdstep. The third step is a step of applying a phosphor coating material36C to the entire surface of the front surface 31 of the insulatinglayer 32, that is, the surface on which the electrode layer 34 isformed. In this step, for example, the phosphor coating material 36C isapplied by printing. In this case, the phosphor coating material 36C isapplied thicker than all of the electrode pairs 34A. In other words, inthis case, the phosphor coating material 36C is applied in the thicknessdirection of the insulating layer 32 so as to cover each bonded surface34A1 from the outer side in the thickness direction (so that each bondedsurface 34A1 is concealed by the phosphor coating material 36C).

<Fourth Step>

FIG. 3D is a diagram showing a start time and an end time of the fourthstep. The fourth step is a step of removing a part of the phosphor layer36 obtained by curing the phosphor coating material 36C and exposing thebonded surface 34A1 of all of the electrode pairs 34A. Here, in a casewhere the binder of the phosphor coating material 36C is, for example, athermosetting resin, the phosphor coating material 36C is cured byheating and then laser light is selectively emitted to a portion of thephosphor layer 36 on each bonded surface 34A1 by using a two-dimensionallaser processing device (not shown). As a result, a portion of thephosphor layer 36 on each bonded surface 34A1 and a portion of theelectrode pair 34A near each bonded surface 34A1 are ablated, and eachbonded surface 34A1 is exposed. As a result of the above, the phosphorsubstrate 30 of the present embodiment is manufactured.

In addition to the above method, this step may be performed by, forexample, the following method. In a case where the binder of thephosphor coating material 36C is, for example, a UV curable resin(photosensitive resin), a mask pattern is applied to a portion (coatingmaterial opening) overlapping each bonded surface 34A1 to expose UVlight, the portion other than the mask pattern is UV-cured, and anon-exposed portion (uncured portion) is removed with a resin removingliquid to expose each bonded surface 34A1. After that, in general,after-curing is performed by applying heat (photo development method).

<Fifth Step>

FIG. 3E is a diagram showing a start time and an end time of the fifthstep. The fifth step is a step of mounting a plurality of light emittingelements 20 on the phosphor substrate 30. In this step, a solder pasteSP is printed on each bonded surface 34A1 of the plurality of electrodepairs 34A of the phosphor substrate 30 (that is, bonded surface 34A1 inwhich the CSP mounted electrode is determined by a printing method, acoating method with a dispenser (not shown), or other methods withrespect to the phosphor layer 36), and the solder paste SP is melted ina state where each electrode of the plurality of light emitting elements20 is positioned on each bonded surface 34A1. After that, in a casewhere the solder paste SP is cooled and solidified, each light emittingelement 20 is bonded to each electrode pair 34A. That is, this step isperformed by, for example, a reflow step.

The above is the description of the method for manufacturing the lightemitting substrate 10 of the present embodiment.

<<Light Emitting Operation of Light Emitting Substrate of PresentEmbodiment>>

Next, the light emitting operation of the light emitting substrate 10 ofthe present embodiment will be described with reference to FIG. 4. FIG.4 is a diagram for explaining the light emitting operation of the lightemitting substrate 10 of the present embodiment.

First, in a case where an operation switch (not shown) for operating theplurality of light emitting elements 20 is turned on, the power supplyis started from the external power source (not shown) to the electrodelayer 34 through the connector (not shown), the plurality of lightemitting elements 20 emit light L radially, and some light L reaches thefront surface 31 of the phosphor substrate 30. Hereinafter, the behaviorof the light L will be described separately according to a travelingdirection of the emitted light L.

Some light L emitted from each light emitting element 20 is emitted tothe outside without being incident to the phosphor layer 36. In thiscase, a wavelength of the light L remains as the same as the wavelengthof the light L, in a case of being emitted from each light emittingelement 20.

In addition, the light of the LED 22 itself in some light L emitted fromeach light emitting element 20 is incident to the phosphor layer 36.Here, the “light of the LED 22 itself in some light L” described aboveis light of the emitted light L that is not color-converted by thephosphor (phosphor sealing layer 24) of each light emitting element 20(CSP itself), that is, light of the LED 22 itself (for example, blue(wavelength is approximately 470 nm) color). Then, in a case where thelight L of the LED 22 itself collides with the phosphor dispersed in thephosphor layer 36, the phosphor excites and emits excitation light.Here, the reason why the phosphor is excited is that the phosphordispersed in the phosphor layer 36 uses a phosphor (visible lightexcited phosphor) having an excitation peak in blue light. Along withthis, a part of the energy of the light L is used for exciting thephosphor, so that the light L loses a part of the energy. As a result,the wavelength of the light L is converted (wavelength conversion isperformed). For example, depending on the type of phosphor in thephosphor layer 36 (for example, in a case where a red CASN is used asthe phosphor), the wavelength of light L becomes longer (for example,650 nm or the like). In addition, the excitation light in the phosphorlayer 36 may be emitted from the phosphor layer 36 as it is, but some ofthe excitation light goes to the lower electrode layer 34. Then, some ofthe excitation light is emitted to the outside by reflection on theelectrode layer 34. As described above, in a case where the wavelengthof the excitation light by the phosphor of the phosphor layer 36 isequal to or more than 600 nm, the reflection effect can be expected,even if the electrode layer 34 is formed of Cu. The wavelength of thelight L differs from the above example depending on the type of thephosphor in the phosphor layer 36, but in any case, the wavelengthconversion of the light L is performed. For example, in a case where thewavelength of the excitation light is less than 600 nm, a reflectioneffect can be expected, if the electrode layer 34 or its surface isformed of, for example, Ag (plating). In addition, a white reflectivelayer may be provided on the lower side (insulating layer 32 side) ofthe phosphor layer 36. The reflective layer is provided with, forexample, a white coating material such as a titanium oxide filler.

As described above, the light L emitted by each light emitting element20 (the light L emitted radially by each light emitting element 20) isirradiated to the outside together with the excitation light through aplurality of optical paths as described above. Therefore, in a casewhere a light emission wavelength of the phosphor contained in thephosphor layer 36 and a light emission wavelength of the phosphor(phosphor sealing layer 24) that seals (or covers) the LED 22 of thelight emitting element 20 (CSP) are different from each other, the lightemitting substrate 10 of the present embodiment emits a bundle of thelight L, in a case of being emitted by each light emitting element 20,by setting it as a bundle of the light L containing the light L at awavelength different from the wavelength of the light L, in a case ofbeing emitted by each light emitting element 20, together with theexcitation light. For example, the light emitting substrate 10 of thepresent embodiment emits combined light of light (wavelength) emitted bythe light emitting element 20 and light (wavelength) emitted from thephosphor layer 36.

Meanwhile, in a case where a light emission wavelength of the phosphorcontained in the phosphor layer 36 and a light emission wavelength ofthe phosphor (phosphor sealing layer 24) that seals (or covers) the LED22 of the light emitting element 20 (CSP) are the same as each other (ina case of the same correlated color temperature), the light emittingsubstrate 10 of the present embodiment emits a bundle of the light L, ina case of being emitted by each light emitting element 20, by setting itas a bundle of the light L containing the light L at a wavelength sameas the wavelength of the light L, in a case of being emitted by eachlight emitting element 20, together with the excitation light.

The above is the description of the light emitting operation of thelight emitting substrate 10 of the present embodiment.

<<Effect of Present Embodiment>>

Next, the effect of the present embodiment will be described withreference to the drawings.

<First Effect>

The first effect will be described by comparing the present embodimentwith a comparative embodiment (see FIG. 5) described below. Here, in thedescription of the comparative embodiment, in a case of using the sameconstituent elements and the like as in the present embodiment, the samenames, symbols, and the like as in the case of the present embodimentare used for the constituent elements and the like. FIG. 5 is a diagramfor explaining a light emitting operation of a light emitting substrate10A of a comparative embodiment. The light emitting substrate 10A of thecomparative embodiment (a substrate 30A on which the plurality of lightemitting elements 20 are mounted) has the same configuration as thelight emitting substrate 10 (phosphor substrate 30) of the presentembodiment except that the phosphor layer 36 is not provided.

In the case of the light emitting substrate 10A of the comparativeembodiment, the light L emitted from each light emitting element 20 andincident to the front surface 31 of the substrate 30A is reflected orscattered without converting the wavelength. Accordingly, in the case ofthe substrate 30A of the comparative embodiment, it is not possible toadjust the light to light having light emission color different from thelight emitted by the light emitting element 20, in a case where thelight emitting element 20 is mounted. That is, in a case of the lightemitting substrate 10A of the comparative embodiment, it is not possibleto adjust the light to light having light emission color different fromthe light emitted by the light emitting element 20.

On the other hand, in the case of the present embodiment, when seen fromthe thickness direction of the insulating layer 32, the phosphor layer36 is disposed on the surface 31 of the insulating layer 32 that isaround each bonded surface 34A1 with each light emitting element 20.Accordingly, some of the light L emitted radially from each lightemitting element 20 is incident to the phosphor layer 36,wavelength-converted by the phosphor layer 36, and irradiated to theoutside. In this case, some of the light L radially emitted from eachlight emitting element 20 is incident to the phosphor layer 36 to excitethe phosphor contained in the phosphor layer 36 and generate theexcitation light.

Here, FIG. 6 is a graph showing a result of a first test of thecorrelated color temperature of the light emitting substrate 10 of thepresent embodiment. In addition, FIG. 7 is a graph showing a result ofthe second test of the correlated color temperature of the lightemitting substrate 10 of the present embodiment.

The first test is a test to obtain a result by investigating arelationship between a current (mA) and a correlated color temperature(K) of the plurality of light emitting elements 20, in a case where thepower is supplied to the light emitting substrate 10 including theplurality of light emitting elements 20 having the correlated colortemperature approximately at 2200 K to 2300 K to generate light. Here,HE (1) and HE (2) show two examples in a case where the structure of theelectrode layer 34 is the same as that of the present embodiment. As theresult of FIG. 6, in any case, the correlated color temperature of thelight L emitted by the light emitting substrate 10 is lower than thecorrelated color temperature of the plurality of light emitting elements20. That is, in the case of the present embodiment, the correlated colortemperature could be shifted by providing the phosphor layer 36.

In addition, the second test is a test to obtain a result byinvestigating a relationship between a current (mA) and a correlatedcolor temperature (K) of the plurality of light emitting elements 20, ina case where the power is supplied to the light emitting substrate 10including the plurality of light emitting elements 20 having thecorrelated color temperature approximately at 2900 K to 3000 K togenerate light. Here, HE (1) shows a case where the structure of theelectrode layer 34 is the same as that of the present embodiment. As theresult of FIG. 7, the correlated color temperature of the light Lemitted by the light emitting substrate 10 is lower than the correlatedcolor temperature of the plurality of light emitting elements 20. Thatis, in the case of the present embodiment, the correlated colortemperature could be shifted by providing the phosphor layer 36.

Therefore, according to the phosphor substrate 30 of the presentembodiment, in a case where the light emitting element 20 is mounted, itis possible to adjust the light L emitted from the phosphor substrate 30to light having a light emission color different from the light Lemitted by the light emitting element 20. Along with this, according tothe light emitting substrate 10 of the present embodiment, it ispossible to adjust the light L emitted from the phosphor substrate 30 tothe light L having a light emission color different from the light Lemitted by the light emitting element 20. From another point of view,according to the light emitting substrate 10 of the present embodiment,it is possible to irradiate the outside with light L having a lightemission color different from the light L emitted by the light emittingelement 20.

Meanwhile, in a case where a light emission wavelength of the phosphorcontained in the phosphor layer 36 and a light emission wavelength ofthe phosphor (phosphor sealing layer 24) that seals (or covers) the LED22 of the light emitting element 20 (CSP) are the same as each other (ina case of the same correlated color temperature), the light emittingsubstrate 10 of the present embodiment emits a bundle of the light L, ina case of being emitted by each light emitting element 20, by setting itas a bundle of the light L containing the light L at a wavelength sameas the wavelength of the light L, in a case of being emitted by eachlight emitting element 20, together with the excitation light. In thiscase, it is possible to exhibit the effect of alleviating a chromaticityvariation of the mounted light emitting element 20 by the phosphor layer36.

<Second Effect>

In the case of the comparative embodiment, as shown in FIG. 5, spots aregenerated in the light L irradiated to the outside due to an arrangementinterval of each light emitting element 20. Here, the larger the spot oflight L, the larger the glare.

On the other hand, in a case of the present embodiment, as shown in FIG.2B, the periphery of each bonded surface 34A1 is surrounded (over theentire circumference) by the phosphor layer 36, and the phosphor layer36 is also provided between the light emitting elements 20 adjacent toeach other. Therefore, the excitation light is also emitted from theperiphery of each bonded surface 34A1 (periphery of each light emittingelement 20).

Therefore, according to the present embodiment, it is possible to reducethe glare, compared to the comparative embodiment.

In particular, this effect is effective, in a case where the phosphorlayer 36 is provided over the entire surface of the insulating layer 32,specifically, in a case where a region of the front surface 31 of theinsulating layer 32 where the phosphor layer 36 is disposed is a regionthat is 80% or more of the front surface 31.

<Third Effect>

In addition, in the present embodiment, as described above, the phosphorlayer 36 is provided between the adjacent light emitting elements 20(FIG. 2B). In addition, the binder of the phosphor layer 36 has aninsulating property equivalent to that of the binder contained in, forexample, a solder resist. That is, in a case of the present embodiment,the phosphor layer 36 functions as a solder resist.

<Fourth Effect>

In addition, in a case of the present embodiment, for example, thephosphor contained in the phosphor layer 36 is a CASN phosphorcontaining Eu, and the phosphor layer 36 is provided on the wiringportion 34B formed of Cu. Therefore, for example, in a case where eachlight emitting element 20 emits white light L, for example, the CASNphosphor contained in the phosphor layer 36 emits excitation light at awavelength of 600 nm or more, and the excitation light is moreefficiently reflected by Cu, and accordingly, the light emissionefficiency is increased (see FIGS. 6 and 7). In this case, it ispossible to add warm color light to the white light of the lightemitting element 20, and increase a special color rendering index R9value. This effect is particularly effective for pseudo-white usingYAG-based white light (yellow phosphor).

The above is the description of the effect of the present embodiment.

As described above, the present invention has been described withreference to the embodiments and examples described above, but thepresent invention is not limited to the embodiments and examplesdescribed above. The technical scope of the present invention alsoincludes, for example, the following embodiments (modification example).

For example, in the description of the present embodiment, an example ofthe light emitting element 20 is a CSP. However, an example of the lightemitting element 20 may be other than the CSP. For example, it maysimply be equipped with a flip chip. In addition, it can also be appliedto the substrate itself of a COB device.

In addition, in the description of the present embodiment, the pluralityof light emitting elements 20 are mounted on the phosphor substrate 30and the light emitting substrate 10 includes the plurality of lightemitting elements 20. However, considering a mechanism for explaining afirst effect described above, it is clear that the first effect isexhibited even with one light emitting element 20. Therefore, the numberof light emitting elements 20 mounted on the phosphor substrate 30 maybe at least one or more. In addition, the number of light emittingelements 20 mounted on the light emitting substrate 10 may be at leastone or more.

In addition, in the description of the present embodiment, the rearsurface pattern layer 38 is provided on the rear surface 33 of thephosphor substrate 30 (see FIG. 1B). However, considering a mechanismfor explaining the first effect described above, it is clear that thefirst effect is exhibited even if the rear surface 33 of the phosphorsubstrate 30 is not provided with the rear surface pattern layer 38.Therefore, even if the embodiment is different from the phosphorsubstrate 30 and the light emitting substrate 10 of the presentembodiment only in that the rear surface 33 is not provided with therear surface pattern layer 38, it can be said that this embodimentbelongs to the technical scope of the present invention.

In addition, in the description of the present embodiment, the phosphorlayer 36 is, for example, disposed on a portion of the front surface 31of the insulating layer 32 and the electrode layer 34, other than theplurality of electrode pairs 34A (see FIG. 2B). However, considering amechanism for explaining the first effect described above, it is clearthat the first effect is exhibited, even if the phosphor layer is notdisposed over the entire region of the portion of the front surface 31of the phosphor substrate 30 other than the plurality of electrode pair34A. Therefore, even if the embodiment is different from the phosphorsubstrate 30 and the light emitting substrate 10 of the presentembodiment only in that the phosphor layer 36 is disposed in a range ofthe front surface 31 different from that of the present embodiment, itcan be said that this embodiment belongs to the technical scope of thepresent invention.

In addition, in the description of the present embodiment, it has beendescribed that CS-3305A manufactured by Risho Kogyo Co., Ltd. is used asthe motherboard MB in manufacturing the phosphor substrate 30 and thelight emitting substrate 10. However, this is merely an example, anddifferent motherboard MBs may be used. For example, the thickness of theinsulating layer, the thickness of the copper foil, and the like may notbe limited to the standard specifications of those of CS-3305Amanufactured by Risho Kogyo Co., Ltd., and particularly, the thicknessof the copper foil may be thicker.

The light emitting substrate 10 of the present embodiment (including themodification example thereof) can be applied to a lighting device incombination with other constituent elements. Other constituent elementsin this case are a power source that supplies electric power for causingthe light emitting element 20 of the light emitting substrate 10 to emitlight, and the like.

This application claims priority based on Japanese Patent ApplicationNo. 2018-244543 filed on Dec. 27, 2018, the entire disclosure of whichis incorporated herein.

1. A phosphor substrate having at least one light emitting elementmounted on one surface, the phosphor substrate comprising: an insulatingsubstrate; an electrode layer disposed on one surface of the insulatingsubstrate and bonded to the light emitting element; and a phosphor layerwhich is disposed on one surface of the insulating substrate andincludes a phosphor in which a light emission peak wavelength, in a casewhere light emitted by the light emitting element is used as excitationlight, is in a visible light region, wherein a bonded surface of asurface of the electrode layer facing an outer side in a thicknessdirection of the insulating substrate, the bonded surface being bondedto the light emitting element, is positioned further on the outer sidein the thickness direction than a non-bonded surface which is a surfaceother than the bonded surface, and at least a part of the phosphor layeris disposed around the bonded surface.
 2. A phosphor substrate having aplurality of light emitting elements mounted on one surface, thephosphor substrate comprising: an insulating substrate; an electrodelayer which is disposed on one surface of the insulating substrate andbonded to the plurality of light emitting elements; and a phosphor layerwhich is provided on one surface of the insulating substrate andincludes a phosphor in which a light emission peak wavelength, in a casewhere light emitted by the plurality of light emitting elements is usedas excitation light, is in a visible light region, wherein a bondedsurface of a surface of the electrode layer facing an outer side in athickness direction of the insulating substrate, the bonded surfacebeing bonded to the light emitting element, is positioned further on theouter side in the thickness direction than a non-bonded surface which isa surface other than the bonded surface, and at least a part of thephosphor layer is disposed around the bonded surface.
 3. The phosphorsubstrate according to claim 2, wherein at least a part of the phosphorlayer is disposed in a region other than a region of the one surface ofthe insulating substrate where the electrode layer is disposed.
 4. Thephosphor substrate according to claim 2, wherein at least a part of thephosphor layer is disposed on the non-bonded surface.
 5. The phosphorsubstrate according to claim 1, wherein a surface of the phosphor layeron the outer side in the thickness direction is positioned further onthe outer side in the thickness direction than the bonded surface. 6.The phosphor substrate according to claim 1, wherein the light emittingelement is formed as a chip sized package (CSP) in which an LED isincorporated.
 7. The phosphor substrate according to claim 6, wherein acorrelated color temperature of the phosphor is set to a correlatedcolor temperature which is different from a correlated color temperatureof a phosphor contained in the CSP.
 8. The phosphor substrate accordingto claim 6, wherein a correlated color temperature of the phosphor isset to a correlated color temperature which is the same as a correlatedcolor temperature of a phosphor contained in the CSP.
 9. A lightemitting substrate comprising: the phosphor substrate according to claim1; and at least one light emitting element bonded to the bonded surface.10. The light emitting substrate according to claim 9, wherein the lightemitting element is formed as a chip sized package (CSP) in which an LEDis incorporated.
 11. The light emitting substrate according to claim 10,wherein a correlated color temperature of the phosphor is set to acorrelated color temperature which is different from a correlated colortemperature of a phosphor contained in the CSP.
 12. The light emittingsubstrate according to claim 10, wherein a correlated color temperatureof the phosphor is set to a correlated color temperature which is thesame as a correlated color temperature of a phosphor contained in theCSP.
 13. A lighting device comprising: the light emitting substrateaccording to claim 9; and a power source which supplies electric powerfor causing the light emitting element to emit light.
 1. A phosphorsubstrate having at least one light emitting element mounted on onesurface, the phosphor substrate comprising: an insulating substrate; anelectrode layer disposed on one surface of the insulating substrate andbonded to the light emitting element; and a phosphor layer which isdisposed on one surface of the insulating substrate and includes aphosphor in which a light emission peak wavelength, in a case wherelight emitted by the light emitting element is used as excitation light,is in a visible light region, wherein a bonded surface of a surface ofthe electrode layer facing an outer side in a thickness direction of theinsulating substrate, the bonded surface being bonded to the lightemitting element, is positioned further on the outer side in thethickness direction than a non-bonded surface which is a surface otherthan the bonded surface, and at least a part of the phosphor layer isdisposed around the bonded surface.
 2. A phosphor substrate having aplurality of light emitting elements mounted on one surface, thephosphor substrate comprising: an insulating substrate; an electrodelayer which is disposed on one surface of the insulating substrate andbonded to the plurality of light emitting elements; and a phosphor layerwhich is provided on one surface of the